This invention relates to the hydroconversion of heavy petroleum oil and, in particular, is directed to the use of a soluble or dispersible metal salt of a fatty acid to catalyze the hydroconversion of sulfur-containing highboiling petroleum oils.
The use of homogeneous catalysts is well known. Further, the use, per se, of metal-containing organic compounds to catalyze hydrocarbon conversions is also well known and such materials have been used to effect coversion of higher boiling fractions to lower boiling products, as well as to effect the reduction of sulfur and/or nitrogen and other contaminants in petroleum fractions. Thus, for example, U.S. Pat. No. 1,876,270 of Zorn discloses the destructive hydrogenation (also knwon as hydrocracking) of such hydrocarbon mixtures as gas oils through the use of Group III to VII metal salts of 1,3 diketones. These metal salts are coordinated compounds which decompose under the reaction conditions producing the metal in a free state which acts as a catalyst. Metal salt concentrations of above 3.5 wt. % (based on the metal salt compound) are found effective. U.S. Pat. No. 2,091,831 of Pongratz et al discloses the hydroconversion of hydrocarbon mixtures with Group IV or VIII metal salts of naphthenic, oleic or stearic acids. Such hydrocarbon mixtures as tars, residuum and bitumens are said to be converted to more useful products under hydrocracking conditions which include temperatures of 300.degree. to 700.degree. C. These metal salts do not decompose but act as true catalysts when added in concentrations of 4 to 20 wt. %, based on the salt (or about 1 to 3%, based on the metal). U.S. Pat. No. 3,131,142 of Mills discloses the use of metal salts of carboxylic, phenolic or naphthenic acids for the hydrocracking of such heavy oils as topped crude, gas oils, cycle oils, residuum, tars, etc. Salts of the Group II to VIII metals are disclosed and useful concentrations of 0.1 to 1 wt. %, based on the metal, are disclosed as being effective for hydrocracking purposes. Hydrocracking conditions include temperatures of 650.degree. to 900.degree. F., pressures of 500 to 10,000 psig and flow rates of 0.01 to 15 LHSV. All of these patents are concerned with homogeneous catalysis wherein the catalyst material is either oil-soluble or dispersible in the oil in finely divided form. In all of these prior art processes, effective concentrations of the homogeneous catalysts are at least 0.1 wt. %, based on the metal, or in excess of about 2.5 wt. %, based on the metal salt. Because these metal organic salts are often expensive and their use in high concentrations can affect the economic attractiveness of a process, hydroconversion processes utilizing trace amounts of homogeneous catalyst may be commercially attractive.